Member postings for john fletcher 1

Not claiming to be an expert in this matter at all. Only to say one of my friends had a similar problem. Ian took the lot off his mill and set it up on his wooden work bench no trouble at all, put it back on the mill and the problem was back again. So he electrically insulated each component of the digital read out from the metal work on the mill using paper, every thing now works fine. Could this be the answer ? John

I've already copied the article for Andy, they were published in 20th January 1989 and 21st December 1990. The castings are rough on the RDM 350 but I think the important parts are alright. I must have had the machine for about 30 years. Prior to fitting an inverter with speed control, there was another article in MEW or ME which I carried out. The slowest speed was too fast and so I fitted an extra pulley from a front loader washing machine. Basically it was a modified drum drive shaft stub, with a 25mm thick disc fitted on the no pulley end. That disc dropped with a tight fit into the centre/ middle pulley of the mill. I drilled through the disc and into the centre pulley, the centre pulley was threaded and the disc drilled for clearance. Now the new adapter could be attached to the centre pulley of the mill and by use of linked belt to the motor a very slow speed was available. since fitting an inverter the adapter is redundant. If possible I would like a copy of Jeff's idea.John

Hello Andy, I have RDM350 and have carried out all the mods which George Turner described in ME years ago and a few others as well. Mine was preowned but never actually used, had it more than 20 years and satisfied with it. 5 or 6 years ago I fitted a second hand inverter to the machine together with a 3 phase motor, that made a lot of difference with the finish. Prior to that I had made a flywheel which fits under the spindle pulley, looking for a better finish. Whilst on with the inverter job I made a digital read out from an article in MEW 3 or 4 years ago. About 18 years ago I made power traverse using an up/down window motor, together with speed control. Never ending but its been a good machine, with a few faults which in life you learn how to over come. 60 years ago in my wildest dream would never have thought one day I might own and have use of a milling machine. if you would like copies of George Turners mods I will copy them and pop them in the post to you. I will your address so please send me a PM.John

There was good article in MEW a couple of years back. One version was to fit a ABS brake sensor adjacent to the Myford super 7 bull wheel it having 60 teeth, feeding its output to a LED display. I did this to my lathe and it works very well. The other method was to make a disc with 60 slots and use an optical slot coupler again to counter slots. I did the this to my mill using a piece of printed circuit board as the base for the 60 slots. Also I've seen on the ebay a unit for doing much as what I have just mentioned for about £6.John

Its only the control circuit which is 110 volt NOT the entire machine. So when you went for the VFD you weren't wasting your money.John

To Richard above, I have a circuit diagram and list of components of the control board and will send you a copy. Please send me a pm with your home address. and I'll pop it in the post. I had a very old copy of the circuit diagram and some one here redrew it, made a good job of it ,now things are much clearer. The motor is a 110 volt DC shunt wound, I've tested the motor circuit for a friend who owns a Bridgeport Mill using a 110 volt site transformer and a bridge rectifier separately from the speed board , just to verify that it was the board and not the motor. Also have you checked the speed potentiometer, they get a lot of use and wear. Its a wire wound one obtainable from RS or Farnel. John

As Jason has already said, keep on eye on the motor temperature when its revolving slowly, the fan won't be pulling in the necessary cold air to keep it happy. Is it possible to fit an ex computer fan to help things along ? I have an old inverter on my lathe and the motor has never got very hot when I've had it running on slow speed screw cutting etc. I do know that industrial machine when fitted with inverters often have an extra built in fan to keep things from over heating when the motor is running at slow speeds. Give it a try and keep popping your hand on the motor. Modern motors run very hot compared to the older ones. John

Just seen an advert for BECO washing machines, its says now fitted with an inverter powered motor. Might be an idea to look out for a scrap one in say 5 years time. It would be interesting to see a circuit diagram and find out if it would be possible to re program the inverter for workshop use. Keep your eye open. John

You said the motor is a Crompton Parkinson single phase motor. I have just had a look at my motor note book and it says a split phase or capacitor start motor can be reversed by changing over wires BLACK and BLUE. I made a picture of the terminal block and there was three terminals A, Z and AZ. To make a split phase into a cap start remove the link between A and AZ and its place fit the capacitor. Others more knowledgeable than me on the Centec machine suggest you need a larger motor, so it maybe time to fit an inverter and three phase motor. John

Before spending a £100 or so on a dehumidifier, have a look in your local sale room, here they are all PAT tested and they give your a 24 hour guarantee. I've seen a lots for sale and they haven't made much. I've had one for at least 20 years and its worked wonders, as some one said they don't work at low temperature or mine doesn't. Insulation is the answer keep the workshop nice and warm, not forgetting the doors.John

Regarding the inverter or motor which has little or no torque can you not locate a model engineer some where close by you who can help you out. I just wonder if the motor is still connected in Star. Have you a multi meter which you can safely use to measure the out put voltage or have you another motor to which you can carry out a test. John

Whilst you have access to the motor terminal its a good idea to mark each separate winding 1 end and 2 end so that its easy to reconnect the motor into delta for 240 volt running. Do ensure you connect a winding 1 end to a winding 2 end other wise you get strange results. If you are unsure about delta connection ask here, some one else will tell you how to do it. John

I'm not absolutely certain but pretty sure your motor can be altered to 240 volt Delta. Can you send a picture of the terminal box, if you have 6 terminals with a wire or brass links across three of them then it an easy job. There was an excellent article on this site a few weeks ago on just that topic. The person carrying out the reconnection, posted a lot of very good informative pictures together with a step by step explanation. Have a look on more last posts or view all topic, if you still can't find contact Neil he will know. John

There was a good article in MEW some time ago, it counted the 60 teeth on a Myford lathe,can't remember when but Neil will know. For my bench top mill, I made a disc with 60 slots using printed circuit material, and used a slot optical coupler to do the counting. Very good, but those little kits from HK take some beating, how do they do it ? John

To stevetee. My son has recently bought a BSA 350 to restore. Do you know if the same wiring mod is applicable to it as well. No doubt some one will know. Also I think fitting a solid state rectifier in place of the Selenium with improve charging as well, but I suppose the purists will say that's not restoration, but modification.John

Yes, the inverter can be plugged into the power meter, I have had one several years now. Mine will measure Volts, amps power factor, Kw, Kwh and you can set the tariff as well, so that you know how much it cost to run your heater, lathe etc. I think Aldi or Lidl had a similar gadget some time ago, worth having. John

Off the topic some what, to Paul Narramore. Paul what was the cost of hiring the 7.5 ton lorry , does that include insurance and does one have to have a HGV licence to drive one. John

As Neil has said there are just three components, you will need to take the drill apart and located the trigger assembly module not always easy, and putting it together again can be a real pain. If you like I can send you a PM regarding testing the Mosfet once you have got the drill apart and have located the MOSfet, which I think might have failed. although I have known the switch to be full of grit etc and its failed. No doubt you have a camera phone take plenty of pictures as you go, as trying to remember where all the location of all the wires later is not easy. Unfortunately other manufacturers switches etc will not fit. You might need to go to a car boot sale and lookout for an identical drill as a source of spare parts. If you do locate the fault and its a complete unit which is needed, a firm by the name of Cars in Boston Lincolnshire has been a good source of spares for me in the past. I think I found them via Google.John

To Mark ,I got it wrong it is CY cable which I used, its a long time ago since I did the wiring and got mixed up. Its all very good reading here and it is also good that people are prepared to share their knowledge and experiences. John

I have three inverters all of different make. I have wired each of them via a 20 amp relay to give No volt release. Each station has a large red e stop button together with a local stop, start, reverse and jog buttons. The control wires are screened ex computer cables and fortunately I don't have a interference problem. I have used Sy screened cable from the inverter to the motor and all three inverters are now mounted in ventilated steel boxes, trying to stop interference escaping. When I set things up I walked around the workshop with a radio seeking out any leakage. I wouldn't consider interrupting the inverter output in anyway the energy has to go somewhere and why should anyone need to disconnect the motor from the inverter output, am I missing some thing? . Anyway that is my experience with inverters and I'm pretty pleased with the inventers. John